Semi-Free Actions with Manifold Orbit Spaces
Documenta mathematica, Tome 25 (2020), pp. 2085-2114
In this paper, we study smooth, semi-free actions on closed, smooth, simply connected manifolds, such that the orbit space is a smoothable manifold. We show that the only simply connected 5-manifolds admitting a smooth, semi-free circle action with fixed-point components of codimension 4 are connected sums of S3-bundles over S2. Furthermore, the Betti numbers of the 5-manifolds and of the quotient 4-manifolds are related by a simple formula involving the number of fixed-point components. We also investigate semi-free S3 actions on simply connected 8-manifolds with quotient a 5-manifold and show, in particular, that there are strong restrictions on the topology of the 8-manifold.
Classification :
55R55, 57K50, 57S17
Mots-clés : circle action, semi-free action, 5-manifolds, 4-manifolds, 8-manifolds
Mots-clés : circle action, semi-free action, 5-manifolds, 4-manifolds, 8-manifolds
@article{10_4171_dm_794,
author = {John Harvey and Martin Kerin and Krishnan Shankar},
title = {Semi-Free {Actions} with {Manifold} {Orbit} {Spaces}},
journal = {Documenta mathematica},
pages = {2085--2114},
year = {2020},
volume = {25},
doi = {10.4171/dm/794},
url = {http://geodesic.mathdoc.fr/articles/10.4171/dm/794/}
}
John Harvey; Martin Kerin; Krishnan Shankar. Semi-Free Actions with Manifold Orbit Spaces. Documenta mathematica, Tome 25 (2020), pp. 2085-2114. doi: 10.4171/dm/794
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